Tryptophan, an essential amino acid nutrient having the formula: ##STR2## is converted in part by the body into serotonin and melatonin. This later named compound possesses central nervous system activity. Another metabolite of tryptophan, 5-hydroxytryptophan, has been reported by Antonaccio and Robson (J. Pharm. Pharmacol. 25, 495 [1973]) to cause a decrease in blood pressure in monoamine oxidase-inhibited dogs. Another tryptophan derivative, .alpha.-methyl-5-hydroxytryptophan, has been reported to lower blood pressure in spontaneously hypertensive rats when given at the extremely large dose of 200 mg/kg (Tabei et al., Eur. J. Pharmacol., 7, 39 [1969]). 5-Fluorotryptophan has been reported to interfere with the synthesis of indole from anthranilic acid and inhibit the growth of E. coli (Bergmann, Proc. Konig. Ned. Akad. Wetenschap, Series C, 57, 108 [1954]).
Rozhkov et al. (Zh. Org. Khim. 12[5], 1076 [1976]) have synthesized the structural isomer of tryptophan, having the structure: ##STR3## Rozhkov et al. state no utility for this compound.
Johnson et al have reported that the corresponding .alpha.,.beta.-dehydro compound: ##STR4## is useful as a chromophore intermediate (Biolumin. Progr. Proc. Kanagawa-ken, Jap. 1965, 67; Chem. Abst. 67;53994K [1967]).